In vivo expansion of gene-targeted hepatocytes through transient inhibition of an essential gene

Science Translational Medicine · 2025-02-12 · 6 citations

Homology-directed repair (HDR)–based genome editing is an approach that could permanently correct a broad range of genetic diseases. However, its utility is limited by inefficient and imprecise DNA repair mechanisms in terminally differentiated tissues. Here, we tested Repair Drive, a platform technology for selectively expanding HDR-corrected hepatocytes in adult mice in vivo. Repair Drive involves transient conditioning of the liver by knocking down an essential gene, fumarylacetoacetate hydrolase ( Fah ), and delivering an untargetable version of the essential gene in cis with a therapeutic transgene. We show that Repair Drive increased the percentage of correctly targeted hepatocytes in healthy wild-type mice up to 25%, which resulted in a fivefold increased expression of a therapeutic transgene, human factor IX ( FIX ). Repair Drive was well tolerated and did not induce toxicity or tumorigenesis during a 1-year follow-up. This approach may broaden the range of liver diseases that can be treated with somatic genome editing.

Dissecting the effect of mitochondrial BCAT inhibition in methylmalonic acidemia

JCI Insight · 2025-09-08 · 3 citations

Methylmalonic acidemia (MMA) is a severe metabolic disorder affecting multiple organs because of a distal block in branched-chain amino acid (BCAA) catabolism. Standard of care is limited to protein restriction and supportive care during metabolic decompensation. Severe cases require liver/kidney transplantation, and there is a clear need for better therapy. Here, we investigated the effects of a small molecule branched-chain amino acid transaminase (BCAT) inhibitor in human MMA hepatocytes and an MMA mouse model. Mitochondrial BCAT is the first step in BCAA catabolism, and reduction of flux through an early enzymatic step is successfully used in other amino acid metabolic disorders. Metabolic flux analyses confirmed robust BCAT inhibition, with reduction of labeling of proximal and distal BCAA-derived metabolites in MMA hepatocytes. In vivo experiments verified the BCAT inhibition, but total levels of distal BCAA catabolite disease markers and clinical symptoms were not normalized, indicating contributions of substrates other than BCAA to these distal metabolite pools. Our study demonstrates the importance of understanding the underlying pathology of metabolic disorders for identification of therapeutic targets and the use of multiple, complementary models to evaluate them.

High-potency MyoAAV capsids enhanced skeletal muscle correction in a mouse model of GSD IIIa

Molecular Therapy — Methods & Clinical Development · 2025-08-18 · 1 citations

vg/kg). Validation in human liver chimeric mice revealed that the MyoAAV vectors and the AAV9 vectors had a similar efficiency in transducing human hepatocytes, indicating increased translatability for clinical applications.

CRISPR/Cas9 gene therapy increases the risk of tumorigenesis in the mouse model of hereditary tyrosinemia type I

JHEP Reports · 2025-01-11 · 4 citations

Background & Aims: gene by CRISPR gene therapy. Both treatments block flux through tyrosine catabolism and thereby prevent the accumulation of toxic catabolites in HT-I. Methods: gene. Primary endpoints were survival, urine biochemistry, liver (immuno)histochemistry, and genetic analyses. Results: but showed on-and-off target vector integrations. Conclusions: CRISPR gene therapy increases the risk of hepatocellular cancer in the mouse model of HT-I. Because HT-I is characterized by inherent cancer susceptibility, this severe adverse event exposes the potential limitations of CRISPR gene therapy in cancer-prone disorders. Impact and implications: Not much is known about the long-term consequences of somatic gene editing. Our study investigates CRISPR gene therapy in tyrosinemia type I using viral vectors. Although the CRISPR-based therapy effectively treated the metabolic condition, it was associated with a higher incidence of liver cancer than the current standard of care. These findings highlight the potential risks of using CRISPR gene therapy in conditions predisposed to cancer development.

A novel treatment strategy utilizing panobinostat for high-risk and treatment-refractory hepatoblastoma

Journal of Hepatology · 2024-01-21 · 30 citations

A humanized mouse model for adeno-associated viral gene therapy

Nature Communications · 2024-03-04 · 10 citations

Abstract Clinical translation of AAV-mediated gene therapy requires preclinical development across different experimental models, often confounded by variable transduction efficiency. Here, we describe a human liver chimeric transgene-free Il2rg −/− /Rag2 −/− /Fah −/− /Aavr −/− (TIRFA) mouse model overcoming this translational roadblock, by combining liver humanization with AAV receptor (AAVR) ablation, rendering murine cells impermissive to AAV transduction. Using human liver chimeric TIRFA mice, we demonstrate increased transduction of clinically used AAV serotypes in primary human hepatocytes compared to humanized mice with wild-type AAVR. Further, we demonstrate AAV transduction in human teratoma-derived primary cells and liver cancer tissue, displaying the versatility of the humanized TIRFA mouse. From a mechanistic perspective, our results support the notion that AAVR functions as both an entry receptor and an intracellular receptor essential for transduction. The TIRFA mouse should allow prediction of AAV gene transfer efficiency and the study of AAV vector biology in a preclinical human setting.

Ex vivo gene editing and cell therapy for hereditary tyrosinemia type 1

Hepatology Communications · 2024-04-26 · 4 citations

BACKGROUND: We previously demonstrated the successful use of in vivo CRISPR gene editing to delete 4-hydroxyphenylpyruvate dioxygenase (HPD) to rescue mice deficient in fumarylacetoacetate hydrolase (FAH), a disorder known as hereditary tyrosinemia type 1 (HT1). The aim of this study was to develop an ex vivo gene-editing protocol and apply it as a cell therapy for HT1. METHODS: We isolated hepatocytes from wild-type (C57BL/6J) and Fah-/- mice and then used an optimized electroporation protocol to deliver Hpd-targeting CRISPR-Cas9 ribonucleoproteins into hepatocytes. Next, hepatocytes were transiently incubated in cytokine recovery media formulated to block apoptosis, followed by splenic injection into recipient Fah-/- mice. RESULTS: We observed robust engraftment and expansion of transplanted gene-edited hepatocytes from wild-type donors in the livers of recipient mice when transient incubation with our cytokine recovery media was used after electroporation and negligible engraftment without the media (mean: 46.8% and 0.83%, respectively; p=0.0025). Thus, the cytokine recovery medium was critical to our electroporation protocol. When hepatocytes from Fah-/- mice were used as donors for transplantation, we observed 35% and 28% engraftment for Hpd-Cas9 ribonucleoproteins and Cas9 mRNA, respectively. Tyrosine, phenylalanine, and biochemical markers of liver injury normalized in both Hpd-targeting Cas9 ribonucleoprotein and mRNA groups independent of induced inhibition of Hpd through nitisinone, indicating correction of disease indicators in Fah-/- mice. CONCLUSIONS: The successful liver cell therapy for HT1 validates our protocol and, despite the known growth advantage of HT1, showcases ex vivo gene editing using electroporation in combination with liver cell therapy to cure a disease model. These advancements underscore the potential impacts of electroporation combined with transplantation as a cell therapy.

Circadian dysfunction induces NAFLD-related human liver cancer in a mouse model

Journal of Hepatology · 2023-10-27 · 47 citations

RESCUE OF GLUTARIC ACIDURIA TYPE I MICE BY LIVER DIRECTED THERAPIES

Molecular Genetics and Metabolism · 2023-02-28 · 1 citations

Rescue of glutaric aciduria type I in mice by liver-directed therapies

Science Translational Medicine · 2023-04-19 · 26 citations

Glutaric aciduria type I (GA-1) is an inborn error of metabolism with a severe neurological phenotype caused by the deficiency of glutaryl–coenzyme A dehydrogenase (GCDH), the last enzyme of lysine catabolism. Current literature suggests that toxic catabolites in the brain are produced locally and do not cross the blood-brain barrier. In a series of experiments using knockout mice of the lysine catabolic pathway and liver cell transplantation, we uncovered that toxic GA-1 catabolites in the brain originated from the liver. Moreover, the characteristic brain and lethal phenotype of the GA-1 mouse model was rescued by two different liver-directed gene therapy approaches: Using an adeno-associated virus, we replaced the defective Gcdh gene or we prevented flux through the lysine degradation pathway by CRISPR deletion of the aminoadipate-semialdehyde synthase ( Aass ) gene. Our findings question the current pathophysiological understanding of GA-1 and reveal a targeted therapy for this devastating disorder.